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The analytical testing of Cement and Fly Ash is done throughout the year in our laboratory, and involves most of the testing that this laboratory performs. We receive samples from the mills that produce the product as well as samples from the highway projects that the represented material is used on. The frequency of project sampling is determined by the Materials Sampling Guide. All samples are initially sent to the Concrete lab, and they in turn send the samples requiring chemical analysis to us. We then report our results to them, and they issue a report containing the results of both laboratories.

Pictured above (on the left) is the Desiccators and Balances work area. The balances are accurate to 0.0001 of a gram and are used to weigh out a sample for “wet” testing. The desiccators are used to cool down and/or keep the crucibles from being contaminated by moisture. Ceramic crucibles are used for the Insoluble Residue (IR) test. Platinum crucibles are used for the Loss on Ignition (LOI) test that is performed with the Blast Furnace pictured above on the right.

This is the Flame Photometer, which is used to provide the final results of the “wet” alkalis testing for both cement and fly ash. It tests the samples to an accuracy of 0.01% for Sodium and Potassium content. Before we received the X-Ray Fluorescent Spectrometer, this instrument’s main use was for the Equivalent Alkali test for cement. Now its predominant use is to test fly ash with excessive (out of spec.) equivalent alkali results and provide us with the 28-day Available Alkalis result.

In the past, “wet” chemical testing provided all of the results for the items tested in this lab, including cement and fly ash. But since 1992, the bulk of our cement and fly ash testing changed to analytical instrumentation methods. Wet testing is now used only only for those tests mentioned in the above paragraphs.

Our methods and instrumentation are now federally certified through the National Institute of Standards and Technology.

Above-left, we have the balance for weighing out samples to an accuracy of 0.0001 grams. The sample is then placed into a grinding cup and then the grinder, which is the gray unit in the center of the left-hand picture. After grinding, the sample is then transferred to an aluminum sample cup with Boric Acid backing, and then crushed to a pellet form with the blue colored press, to the right of the grinder. The pellet is then placed into the spectrometer (the photo on the right) for analysis.